The present invention relates generally to computer systems and, more particularly, to the automatic and continual adjustment of parameters to values that result in improved system performance even as the workload on the system changes.
Administrators of modem computing systems generally have various parameters available that can be adjusted or configured to values that result in improved performance of the system. Size of swap space, memory dedicated to buffer-cache, maximium number of processes permitted, and maximum application data size are examples of such parameters that could be so adjusted.
With limited success, various techniques have been used to make these parameter adjustments. One common solution to this problem is for the administrator or operator to learn the details of the inner workings or operation of each application, and then speculate as to the optimal configuration of the computer system. This approach has several disadvantages: (1) it is extremely time consuming, especially since it must be repeated as each new application or workload is brought into the system, (2) there is frequently insufficient data available from the vendor of the applications to do this with any precision, (3) it is an error prone process as there are often unforseen dependencies which makes such speculation highly inaccurate, and (4) optimal system parameter values can be dependent upon application usage characteristics, which can vary from time to time.
Another solution to this problem is to build a separate mechanism for each system parameter which influences system performance and which can be adjusted. Each such mechanism would have the capability of measuring system metrics and evaluating whether or not a change in the parameter controlled by that mechanism is called for. For example, such a mechanism could control a system""s virtual memory and could detect when the system either has or is in danger of running out of virtual memory. The mechanism could then recommend that the system be reconfigured to increase virtual memory. One problem with this approach is that a separate mechanism must be created for each system parameter that it is desirable to control.
Thus, there is a need for a method by which a computer system can be more effectively and efficiently improved. In particular, there is a need for a method to automatically and continually adjust system parameters to obtain improved system performance, even as the workload on the system changes.
In representative embodiments, the present patent document discloses methods for automatically making minor adjustments to computer system parameters and comparing long-term associated performance changes in order to set parameter values so as to obtain improved system performance. The time frame over which a change in a system parameter and the associated system performance change is averaged is adjustable, thus permitting evaluation over shorter or longer periods of times as deemed appropriate. An objective measure of system performance should be defined prior to implementation of the present methods. For transaction based systems, average system response-time for a given demand on the system could be, for example, such a measure. For systems executing batch-type workloads, system throughput may be used as the indicator of how well the system is performing. Also needed is a means for incrementally adjusting the value of each adjustable system parameter that influences system performance.
As the computer system runs, the representative embodiment of the present patent document adjusts parameter values over a predetermined interval. As such changes are made, system performance is measured and beneficial changes are implemented.
Representative embodiments as described in the present patent document are advantageous in that they take very little time or effort on the part of the system operator to arrive at an optimal or near optimal system configuration. Additionally, as the usage characteristics and load on the system change, this method finds and recommends improvements to the system, without requiring the operator to continuously monitor and redo previous adjustments that were performed by hand. Another benefit is that this mechanism can be used on a subset of the parameters available on a system. Thus, the operator may choose to use this method to look for improvements in obscure or less understood parameters, and make the macroscopic adjustments himself.
Additional advantages of the embodiments disclosed in the present patent document include an ability to choose a range of values for any particular system parameter, as opposed to selecting a particular value for the parameter. The range chosen could be large or small, depending how much is known regarding the impact of a change in the parameter upon system performance. As experience with the system is gained, the permitted range could be automatically reduced. Generally minor improvements in system performance would not require as large a range of permitted parameter values as might otherwise be available.
Also, if it is determined that the best setting for a parameter is at one extreme of the ranges of values, the operator can be notified and requested to extend the range.
In addition, this method can be used xe2x80x9cofflinexe2x80x9d. This method can be employed on a development or benchmark instance of the application, instead of on the production version. Improved settings could be found with very consumption of operator time, and without risking adverse affects on a production system. The ideal settings obtained using the development system could then be adapted to the production system.